RE Mickle, REMSpC Spray Consulting
G. Rousseau, SOPFIM
SERG Project #1999/04-02
Executive Summary
All treatment (ground or air) programs result in the potential for off-target movement of
pesticides that may pose an environmental risk. While ground applicators can modify
equipment to reduce drift, aerial applicators have fewer options available for drift
minimization. In aerial agricultural programs, vortex modifiers (winglets) have shown
promise in enhancing deposit uniformity and reducing off-target drift. However, in
forestry insecticide programs, wing-tip vortices can promote deposit closer to the spray
line due to a more rapid movement of small drops into the canopy.
A series of trials were completed to compare deposit from two Cessna AgTrucks, one
fitted with Ag-Tips and the other having conventional winglets. Each aircraft used four
Micronair AU4000s producing a drop size distribution around 80µm. Both aircraft were
flown at 15m agl. Sprays were completed in crosswinds ranging from 7-12kph. Deposit
sampling at 5m intervals using Kromekote™ cards and petrie dishes provided drop
density, drop size and volume (BIU/ha) measurements to 300m downwind of the flight
line. In two of the three trials, peak deposit from the conventional AgTruck was closer to
the flight line. The C188 with Ag-Tips had a somwhat broader swath resulting in
enhanced deposit out to 150m from the flight line with reduced deposit beyond and
potentially reduced drift in the far-field. A broader swath with enhanced drop density
could potentially result in improved efficacy.